Rotors for processing liquids, along with modifications and improvements, have been previously described in various patents and disclosures. For example, U.S. Pat. No. 3,901,658 issued on Aug. 26, 1975, discloses a rotor assembly for performing photometric analyses using whole blood samples. A gross blood sample is loaded within a centrally located, removable, cell sedimentation bowl and the red blood cells are centrifugally separated from the plasma. The plasma is then displaced from the sedimentation bowl, and measured subvolumes of plasma are distributed to respective sample analysis cuvettes positioned in an annular array about the rotor periphery. Additional means for adding reagents to the respective cuvettes are also disclosed.
Another example of a rotor device useful in processing liquids is described in U.S. patent application Ser. No. 762,368 filed on Aug. 8, 1985, which was publicly disclosed soon thereafter under the Department of Energy licensing program. This application discloses an apparatus for automatic processing and aliquoting of whole blood samples for analysis in a centrifugal fast analyzer. More particularly, this rotor is designed to prepare precise aliquots of serum samples from whole blood and automatically load the serum samples into serum capillaries. This device includes no provision for diluting the serum samples with reagents or other diluents.
U.S. Pat. No. 4,515,889 issued on May 7, 1985, discloses a method for carrying out analytical determinations by mixing and incubating a sample solution with at least one reagent and optically measuring a parameter in the incubated reaction mixture. The mixing, incubating and measuring are carried out during the action of a centrifugal force exerted by rotation of a rotor. This device includes no provision for separating non-liquid components from liquid mixtures.
U.S. Pat. No. 4,557,600 issued on Dec. 10, 1985, discloses a process and device for the centrifugal control and mixing of limited volumes of fluid, especially in the rotor of a centrifugal analyzer. The device includes at least one baffle chamber, in a flow canal for the fluid the volume of which is greater than the volume of fluid. The baffle is shaped such that when the device is rotated at a sufficiently high first speed of rotation, the fluid remains in the chamber. Upon rotation of the rotor at a second lower speed of rotation, the fluid flows out of the baffle chamber as a result of a boundary surface force. Again, this device includes no means for separating non-liquid components of a liquid mixture.
Accordingly, there is a need in the art for a rotor which can provide sample preparation and placement. More particularly, the device must be able to accept a liquid mixture in a capillary tube, spin it down to separate non-liquid components from liquid components, draw a known volume of the liquid component and mix it with a known volume of a diluent, draw a known volume of the diluted liquid component, and place the known volume of diluted liquid component on an analysis test pad.